Moisés Naím / The Washington Post

“Private Empire” is a big book about big oil, big money and big government. It chronicles how ExxonMobil — the energy behemoth that recently displaced Wal-Mart atop the Fortune 500 list, with more than $450 billion in revenue — operates in failed states, keeping the oil flowing when no one else can, and how it handles hapless bureaucrats charged with regulating it, scientists challenging it, rival companies trying to outsmart it and activists bent on changing it.